Simplify the following expression: $n = \dfrac{z^2 + 5z - 50}{z + 10} $
Solution: First factor the polynomial in the numerator. $ z^2 + 5z - 50 = (z + 10)(z - 5) $ So we can rewrite the expression as: $n = \dfrac{(z + 10)(z - 5)}{z + 10} $ We can divide the numerator and denominator by $(z + 10)$ on condition that $z \neq -10$ Therefore $n = z - 5; z \neq -10$